Alta Hits 23.5 Percent Efficiency with GaAs Thin Film

Alta Devices of Sunnyvale, Calif., in June disclosed how its flexible thin-film gallium arsenide (GaAs) modules achieved a record 23.5 percent con- version efficiency in NREL testing.

“Traditionally, when solar cells are interconnected to form a module, conversion efficiency is compromised because active solar material is covered with metal bus-bars and wires, preventing some of the light from entering the cells,” Laila Mattos, Ph.D., told an audience at an IEEE meeting in Austin, Texas. “In addition, gaps between cells create areas of the module that are not able to convert incident light to electrical energy. We use a self-interconnected technology that eliminates the wires, thus maximizing the cells’ exposure to incident light. The self-interconnected cells form a flexible sheet with no gaps and that can be of any size or aspect ratio.”

Alta expects to begin pilot manufacturing before the end of this year.